In conventional frames of this type a bore is provided in the corner pieces, which bore extends in direction of the screw axis and exits at the peripheral surface which is visible on the finished frame. This interruption of the visible peripheral surface is undesired for aesthetic reasons. Also the bore forms an opening, through which moisture can penetrate into the frame construction which is particularly disadvantageous when used outside. The bore also forms a place for dust and other contaminations to accumulate and can be kept clean only with great difficulty.
The basic purpose of the invention is to construct, in a frame of the above-mentioned type, the connection of the corner piece with an adjacent profile, so that holes for introducing connecting screws are avoided on the visible peripheral surfaces.
This purpose is attained according to the invention by the corner pieces being of hollow construction and having, on at least one end, an end wall through which the screw extends, and by providing a lateral opening in the corner piece adjacent the area of the screw, through which opening the screw is accessible in a direction transverse of its longitudinal direction.
The opening, through which the screw is accessible, can be arranged in the inventive frame always in such a manner as to avoid interfering with the appearance of the visible surfaces. For example, the opening can be arranged on the backside of a frame, which will later be covered up by a backwall. This avoids exposed screw holes into which moisture and dirt can penetrate and which are disadvantageous as to the looks of the frame.
Corner pieces are possible in which on both ends end walls are provided through which screws extend, and other corner pieces are possible which have an insert part at one end. The opening for the access to the screws can extend over the entire length of the corner piece. However, constructions are also possible in which only relatively short access openings, or windows, are provided.
It is particularly advantageous to construct the screw openings in the corner piece end walls as slots. In such a construction it is possible to make the lateral access openings shorter than the screws, since the screws can first be partly screwed into the profiles and then the corner pieces can be laterally pushed onto the profiles.
It is particularly advantageous to provide a corner piece whose cross section has a perimeter shaped approximately like a flattened rectangle, wherein the lateral access opening is located in a short side of such rectangle, such corner piece shape being particularly suited for frames which consist of relatively wide and flat profiles. Since the wide sides of the corner pieces from visible sides of the frame, it is advantageous to provide the lateral opening on the narrow side of the corner piece.
If at the profile-corner piece connection at one corner piece end there is provided only one screw located at a connection point near the lateral access opening for pulling close together the associated profile and corner piece, then it is advantageous to provide an additional connecting point, on the side of the corner piece end opposite to the first mentioned connecting point, wherein at the additional connecting point a further screw engages a flap formed on the corner piece, which further screw extends through the wall of the connected profile and wherein the axis of the further screw extends transversely to the longitudinal direction of the connected profile. This avoids with certainty the formation of a gap between the corner piece and connected profile.
The lateral access opening can be closed with a special lid. The closing can, however, also occur by covering the opening with a backwall or by arranging a further corner piece next to the first-mentioned corner piece. In some cases the lateral access opening may also remain unclosed.
Corner pieces with insert parts are connected by means of screws which are arranged transverse to the longitudinal direction of the profiles. This avoids uncovered screw holes. This connection is also used for a connection of two frames to one another. With this it is for example possible to connect a frameshaped base of a display cabinet with the frame of the display cabinet. Sufficiently long threaded holes are obtained for the screws which extend transverse to the longitudinal direction of the profiles, if one forms special bars within the corner pieces. Through this also, particularly for relatively soft material, tearing out of the thread is avoided. An insert part can be further reinforced by a center rib.
Particularly advantageous are hexagonal-recess screws. Such screws are particularly suited for tightening, if tool engagement in the axial direction of the screws is not possible, since keys for hexagonalrecess screws normally are constructed as bent hexagonal rods.
The corner pieces are advantageously designed as die-cast parts of aluminum. However, the invention is not limited to the use of this material. All suitable materials, thus in particular also plastic, can be utilized.